From: Jeff Layton jlayton@kernel.org
commit b4002173b7989588b6feaefc42edaf011b596782 upstream.
The first thing metric_delayed_work does is check mdsc->stopping, and then return immediately if it's set. That's good since we would have already torn down the metric structures at this point, otherwise, but there is no locking around mdsc->stopping.
It's possible that the ceph_metric_destroy call could race with the delayed_work, in which case we could end up with the delayed_work accessing destroyed percpu variables.
At this point in the mdsc teardown, the "stopping" flag has already been set, so there's no benefit to flushing the work. Move the work cancellation in ceph_metric_destroy ahead of the percpu variable destruction, and eliminate the flush_delayed_work call in ceph_mdsc_destroy.
Fixes: 18f473b384a6 ("ceph: periodically send perf metrics to MDSes") Signed-off-by: Jeff Layton jlayton@kernel.org Reviewed-by: Xiubo Li xiubli@redhat.com Signed-off-by: Ilya Dryomov idryomov@gmail.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- fs/ceph/mds_client.c | 1 - fs/ceph/metric.c | 4 ++-- 2 files changed, 2 insertions(+), 3 deletions(-)
--- a/fs/ceph/mds_client.c +++ b/fs/ceph/mds_client.c @@ -4912,7 +4912,6 @@ void ceph_mdsc_destroy(struct ceph_fs_cl
ceph_metric_destroy(&mdsc->metric);
- flush_delayed_work(&mdsc->metric.delayed_work); fsc->mdsc = NULL; kfree(mdsc); dout("mdsc_destroy %p done\n", mdsc); --- a/fs/ceph/metric.c +++ b/fs/ceph/metric.c @@ -302,6 +302,8 @@ void ceph_metric_destroy(struct ceph_cli if (!m) return;
+ cancel_delayed_work_sync(&m->delayed_work); + percpu_counter_destroy(&m->total_inodes); percpu_counter_destroy(&m->opened_inodes); percpu_counter_destroy(&m->i_caps_mis); @@ -309,8 +311,6 @@ void ceph_metric_destroy(struct ceph_cli percpu_counter_destroy(&m->d_lease_mis); percpu_counter_destroy(&m->d_lease_hit);
- cancel_delayed_work_sync(&m->delayed_work); - ceph_put_mds_session(m->session); }